1. Field of the Invention
This invention relates to the field of methods for the treatment of Herpes Facialis which is a recurrent disease characterized by episodic vesicular eruptions on the lips and peri-oral skin.
2. Description of Related Art
This disease is Oro-facial Herpes Labialis and is a Herpes Virus infection, also known in the vernacular as cold sores, sun sores, or fever blisters. Oro-facial Herpes Labialis is caused predominantly by Herpes Simplex Virus Type-1 (HSV-1), with a minor subset of patients infected with HSV-2. While oro-facial infection with HSV-2 is possible, recurrent HSV-2 eruptions are rare. Initial infection with Herpes Simplex Virus Type-1 (HSV-1) generally causes mild or negligible symptoms. Herpes Labialis (HSV-1) is characterized by a high rate of recurrences, most often at the site of initial infection (recurrent Herpes Labialis). In the United States 40-50% of the adolescent population and 80-90% of the adult population has been exposed to HSV-1 (1). Approximately 40% of the infected population has had a cold sore at one time or another (2) and most people who have had cold sores will have recurrent outbreaks. Over 50 million adults in the United States have 2 or more outbreaks per year. Episodes generally regress within 7-10 days with complete healing by 12-14 days although a flat scar or erythema may persist (3). While recurrent Herpes Labialis is a benign disease that regresses spontaneously, it is highly contagious with high viral titers in blisters and effluent. Herpes Labialis causes physical pain and can also be disfiguring especially in those patients with frequent recurrences (3).
Current treatments for Herpes Labialis can be divided into three major categories: 1) palliative treatment 2) topical antiviral medication 3) systemic antiviral medication. Palliative treatments with numbing agents (lidocaine, tetracaine, benzocaine, benzyl alcohol, camphor, and phenol) and emollients (petrolatum and allantoin) while alleviating some of the discomfort of a recurrence of Herpes Labialis have no effect on the time course or on the frequency of recurrences. There are several topical and systemic antiviral medications that purport to shorten the time course of Herpes Labialis eruptions. Abreva® (docosanol 10% Cream formula), a topical cream which has been approved by the FDA for over the counter (OTC) sale, interferes with the adsorption of virus to cell surface lipid membranes but not with the binding of virions to the cell surface (4). Abreva® (docosanol), which has not been shown to have any direct anti-viral activity (5), has been shown to shorten mean healing time from 7.3 to 5.7 days. For significant response, docosanol must be applied during the prodrome. The prescription antiviral drugs, Zovirax® (acyclovir), Valacyclovir®, penciclovir, and famciclovir used for HSV-1 infections are all analogs of acyclic guanosine. The FDA has not approved these drugs for OTC sale because of possible development of viral resistance (6). Due to low bioavailability, Zoviraxe has but marginal efficacy and application after the prodromal phase has little or no efficacy (7). Treatment with penciclovir in 1% concentration (Denavir® 1%) when started during the prodrome is more effective than Zovirax® in decreasing lesion healing time, alleviation of pain, and viral shedding (7;8). However, application after the prodromal phase has but marginal efficacy with 20-30% reduction in symptoms and time to healing (7). Famvir® (famciclovir) is converted to penciclovir in the body. Famciclovir is active against the same viruses as Acyclovir but has a longer duration of action. Valacyclovil, a valine ester of acyclovir, is another “prodrug,” which is converted to acyclovir in the body. Oral Valtrex® (Valacyclovir) is approved for use in immunocompetent adults as a one day treatment. Oral treatment with these acyclovir produgs shortens duration of Herpes Labialis episodes by approximately 1 day (9).
None of the current topical treatments for HSV-1 infection have proven to be completely effective and no cure is available.